ILLINOIS BIOLOGICAL MONOGRAPHS 



VOLUME XI 



-1°. Z° 2$. 4p So 



DiQptomuS 



Bosmina 



Do p h n i o 



Cyclops 



(heavL) = Diurna I 

 LLiqht ■ Nocturnal 



Nlo per 15 liters of Wa+er 

 10 o no 



CAHN 



PLATE XVI 



